1. Field of the Invention
The invention relates to the determination of the relative hardness and abrasion resistance of industrial film coatings and linings. Such coatings and linings traditionally have been applied to the interior or exterior surfaces of various metallic and non-metallic industrial structures, containers, vessels, pipes, and the like. The purpose of such film coatings and linings is to prevent or retard the corrosion or deterioration of the surfaces to which they are applied. The invention disclosed relates particularly to the determination of the relative hardness and abrasion resistance of film coatings and linings applied to such surfaces.
2. Description of the Prior Art
When industrial film coatings or linings are applied to various metallic and non-metallic surfaces in order to protect against deterioration or corrosion of such surfaces, it often is considered desirable to assess the prospective effectiveness of a particular film coating or lining by determining its relative hardness and abrasion resistance.
Prior to the disclosed invention, there existed two generally used methods for determining the relative hardness and resistance to abrasion of industrial film coatings and linings. In the first method, a readily available hard object is "scratched" along the film coating or lining surface of interest, and human judgment is used to evaluate the depth and width of the created scratch, resulting in a subjective evaluation of the relative hardness and abrasion resistance of the film coating or lining. These "scratches" have been created by such means as: (1) applying a quarter to the film coating or lining surface and drawing or pulling the quarter across the surface; (2) applying a human fingernail to the film coating or lining surface and drawing or pulling the human fingernail across the surface; or (3) applying pencils of various hardnesses to the film coating or lining surface and drawing or pulling a pencil across the surface, as in the ASTM 3363 Pencil Test.
The foregoing means of determining, in the field, the relative hardness and abrasion resistance of industrial film coatings and linings are disadvantageous because of the numerous variables associated with each method, including the amount of force applied to the scratching implement by the test operator, the angle or attitude of the scratching implement as applied to the particular film coating or lining surface, and the hardness or sharpness of the scratching implement itself. These variables result in random, uncontrolled and non-repeatable determinations of relative hardness and abrasion resistance.
A second method previously used to determine the relative hardness and abrasion resistance of industrial film coatings and linings involves the use of various sophisticated electrical or electronic testing devices. Although such devices are capable of producing repeatable and non-random results, such devices generally are not suitable for use "in the field," i.e., at the location for use of the object of interest, but rather must be used in the controlled context and environment of a scientific laboratory or workshop. In addition, these sophisticated devices generally can only be used on horizontal surfaces, and cannot be used to determine the relative hardness and abrasion resistance of film coatings or linings applied to vertical or partially inclined surfaces.